Friction drive apparatus



July 20, 1965 J. L.. coAKLEY x-:TAL 3,195,355

FRICTION DRIVE APPARATUS Filed April 24, 1961 8 Sheets-Sheet 1 July 20, 1965 J. coAKLEY E'l-Al.` 3,195,365

FRICTION DRIVE APPARATUS Filed April 24, 1961 8 SheetS-She6t 2 Q y W m I S N O a `0 u &'.\

Q \Q n m Q Q S2 Q g l I l x l I I tg l H l' .i un qq@ l' I. i1 Q Il 7 E r g I N 1| l L .'NVENTORSZ A JAMES L. COAKLEY HANS A. HUG

July 20,1965 'J. L. COAKLEY Em. 3,195,365

FRIcTIoN DRivE APPARATUS -Filed April 24, 1961 8 sheets-sheet 5 July 20, 1965 Filed April 24. 1961 FRICTION DRIVE APPARATUS J. L. ccAKLE'Y ETAL 8 Sheets-Sheet 4 INVENTRs.-

JAMES L coALEY HANS A. HUG

J. l.. coAKLEY E'rAL. 3,195,365

FRICTION DRIVE APPARATUS July 20,1965

8 Sheets-Sheet 5 Filed April 24, 1961 INVHVTORS: JAMES L.. COAKLEY HANS A. HUG

July 20 1965 J. l.. coAKLEY ETAL 3,195,355

eeeeeeeeeeee t6 April 24, 1961 Il w- QTS Jui? 20 1965 J.- l.. coAKLEY ETAL 3,195,355

FRICTION DRIVE APPARATUS 8 Sheets-Sheet 7 Filed April 24, 1961 July 20, 1965 .1.1.. coAKLl-:Y E'rAl.

FRICTION DRIVE APPARATUS 8 Sheets-Sheet 8 Filed April 24, 1961 & m

INVENTORS: JAMES L. COAKLEY HANS A. HUG

United States Patent() 3,195,365 FRICTIN DRIVE APPARATUS James L. Coalrley, Woodland Hills, Calif., and Hans A. Hug, Norwood, Mass., assignors to American Brake Shoe Company, New York, NY., a corporation of Delaware Filed Apr. 24, 1961, Ser. No. 105,044 16 Claims. (Cl. i4-388) This invention relates to a friction drive apparatus for converting rotary motion and torque into axial displacements and thrust. More particularlythis invention relates to apparatus for increasing the torque and thrust output of friction drive apparatus of the kind in which a ring or roller member is engaged with the periphery of a rotating shaft and is tiltable about the area of engagement with the shaft to provide axial movement of the ring or roller member as a consequence of rotation of the shaft. l

In the co-pending applications of Hans A. Hug, Serial No. 842, and Joseph M. Davin and Hans A. Hug, Serial No. 841,'now Patent No. 3,043,149, both filed January 6, 1960, there are disclosed a number of friction drive arrangements of the aforesaid kind for converting rotary motion and torque into axial displacement and thrust. Thus, in applicationSerial No. 842 there is illustrated and described a friction drive arrangement wherein a pair of counter-rotatable shafts are disposed in closely spaced and parallel relation, and wherein individual rollrings, each having an internal diameter somewhat larger than the external diameter of -a shaft, encircle respective ones of the shafts. Each rollring is biased to a position wherein a portion of the inner periphery of the rollring is frictionally engaged with the portion of the outer periphery of its respective shaft, and the rollrings are further mounted for rotation Within a deck member. So longas the rings are disposed substantially perpendicular to a plane passing through the center lines of the two shafts, the portions of the rings engaged with the shafts traverse circular paths about the periphery of the shafts during rotation of the shafts and the rings and deck member remain at a fixed axial position with respect to the shaft. However, upon tilting the rollrings about an yaxis passing through the areas of engagement with the shafts, the portions of the rings engaged with the shafts are caused to traverse a helical path about the peripheries of the shafts, and the rings are thereby moved axially of the shafts in a direction dependent -upon the direction of rotation of the shafts and the angle at which the rollrings are tilted. By reason of the friction developed between the engaged portions of the rollrings and the shafts, a portion of the radial torque applied to the shafts can be converted to an axial thrust exertable directly on a load device by the rings and deck member during such axial movement. In such an arrangement, the maximum magnitude of the thrust thus made available is determined by the force with which the rings and shafts are engaged with one another and the coefficient of friction between the rings and shafts. Thus, for a friction drive arrangement of this kind to be capable of exerting large axial thrusts, such as thrusts of 500 pounds or larger, it may be necessary to have resort to rather bulky and heavy apparatus.

It is therefore a primary object of this invention to reduce the overall size of friction drive apparatus of the general kind described and yet obtain larger axial thrusts than have heretofore been possible.

In the aforesaid application Serial No. 841 there is disclosed a friction drive apparatus which utilizes parallel shafts and encircling rollrings as outlined hereinabove.

However, the counter-rotatable shafts of the friction drive apparatus disclosed in application Serial No.' 841 are formed with complemental but oppositely disposed conical contours in the portions to be engaged by the rollrings. Thus, the larger diameter end of the conical portion of one shaft is immediately adjacent the smaller diameter end of the conical portion of the other shaft, and Vice versa. Additionally, the rollrings are engaged with one another at their outer peripheries in the portions disposed between the shafts so as to afford a drive means between the shafts, whereby one shaft can be rotated as a consequence of the torque applied to the other shaft. As in the first mentioned friction drive apparatus noted hereinabove with reference to application Serial No. 842, tilting of the rollrings -about the areas of engagement with the shafts is effective to cause the rollrings to be frictionally driven in an axial direction along the shafts. Since the relationship between the radii at whichthe areas of engagement of the rollrings act on the respective shafts is continuously Varied by such axial movement of the rollrings along the shafts, any selected output speed of rotation of one :shaft can be obtained with a given speed of rotation of the other shaft.

The present invention utilizes a differential in the A speeds -of rotation of the shafts in a friction drive apparatus incorporating conical shafts as aforesaid to obtain an increase in the torque available from the driven shaft and convert such increased torque into an axially directed thrust; and such constitutes a specific object of this invention. v

In accordance with one form of the present invention planetary gearing is operatively connected for drive by the respective conical shafts to produce an output torque as a function `of a differential between the speeds of rotationof the respective shafts, and the output torque is in turn converted to an axially directed thrust through a power screw mechanism.

In accordance with another form of the present invention a pair of worms comprising a part of a worm gear mechanism are connected for drive by the conical shafts, and the Worms are effective to impart axial motion to a worm wheel interposed therebetween whenever the worms are rotated at different speeds by the conical shafts.

In yanother form of the present invention the mechanism for converting the differential in the speeds of rotation of the shafts to an axial thrust may take the form of a quite simple screw and nut mechanism in which one shaft directly drives a screw spindle. A nut is threaded on the screw spindle and is adapted to be rotated by the other shaft. So long as the nut and screw spindle are rotated at the same angular velocity the nut remains at the same axial position on the screw spindle. However, should the conical shafts be rotated at different speeds, the nut rotates at a different angular velocity than the screw sprindle, whereupon the nut is moved axially in fa direction dependent upon the relative speeds of rotation of the conical shafts.

In each of the above-noted torque converting mechanisms a very substantial mechanical advantage is obtained through the planetary gear, worm gear and screw spindle and nut mechanisms employed so that the relatively low torque output of the conical shafts is available as a quite large axial thrust in the respective axially movable members of each form of the torque converting mechanism. And to incorporate the foregoing mechanisms for converting rotational torquevto axial thrust in novel friction drive apparatus of the general kind described constitutes further specific objects of the present invention.

In the forms of the invention utilizing the torque converting mechanisms as aforesaid for multiplying the torque output of the conical shafts and converting such Si multiplied torque to an axial thrust, the respective screw, Worm wheel or nut may function as or be connected to an output member for transmitting an axial thrust to a load device. In a neutral position of the rollrings, or other means affording a friction drive between the shafts, the rollrings or drive means traverse a circular path on the peripheries of the conical shafts in the mid portions thereof and said shafts rotate atl equal speeds.V Inxsuch neutral position the friction drive apparatus is in a state of equilibrium wherein no axial motion is imparted to the output member. A control mechanism may preferably be utilized to impart a selected amount of tilt to the rollrings, or other meansl affording a drive between the conical shafts, to move the rollrings or drive means from the neutral position and thereby vary the respective speeds of rotation of vthe shafts and thus produce an axial `displacement in the output member.

It is another object of this invention to sumup the axial movement of the output member and apply a second force of a magnitude dependent upon the extent of the axial movement of said output member in .opposition to the tilting force imparted by the control mechanism. Thus, the force developed by axial movement of the output membery continuously increasesin magnitude with the increasing displacement of the output member and isr effective to` progressively overcome theforce of the control mechanism and thereby cause the drive means to return to the neutral position, thus ending .further axial displacement of thek output member. In this manner the extent of the axial'movement of the output member is related to and is controlled by the magnitude of initial force imparted to the drive means by the control mechanism.

In some instances it is possible that the thrust output member may be required to overcome an 'external resistance of such a'magnitude that the maximum torque available from the driven shaftof the friction drive apparatus would be exceeded. of the rollrings or other drive means on the `conical shafts could occur. siderable damage to the frictioncdrive apparatus; and it is accordingly another object -of this invention to include a thrust-limiting mechanism in friction drive apparatus incorporating planetary gear and worm gear torque converting mechanisms as aforesaid.

Such thrust-limiting mechanism senses the buildup of y the output thrust, and upon a thrust of predetermined magnitude being obtained, the thrust-limiting mechanism is effective to return the drive rings toV a neutral position atV the .mid portions of the conical shafts andk therebyy prevent the development of additional thrust in the.

' `able by axial movement of the axially movable member and connected to the rollring or otherdrive means through i a lost motion connection. In this form of the'invention an output thrust of a predetermined magnitude is effective to shift the fork member to a position wherein the i fork member engages the rollrings ork other drive means and tilts the rollrings or other drive means in a direction to return the rings to the above-described neutral position and thus limit the thrust outputof the torque. converting mechanism, regardless of the axial displacement of Vthe output member as called lfor by the control mechanism.

Other and further objects of the present invention vwill be apparent from the following description and claimsand are illustrated in the accompanying drawings which, by way of illustration, showv preferred embodiments of thel present invention and the principles thereof and what are In such'a case, a condition of slipy Such slippage is quite llikely to cause connow considered to .be the best mode contemplated for applying these principles.` OtherA embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the artvwithout departing from the present invention and the purview ofthe appended claims.

In the drawings:

FIG. 1 is a plan View, partly in section, of one form ofa friction drive apparatus.` constructed 1in accordance with one embodiment-of the present invention and incorporating a planetarygear torque multiplying mechanism;

FIG. 2.is a fragmentary View in side elevation of a controlmechanism, mounted on a sliding support, which can lbe used withdiiferent forms of the .friction drive apparatus illustrated in various figures of the drawings;

FIG. 3 is a fragmentary view in sidfeelevation of another control mechanism, mounted on a xed support, which can be utilized with various forms of the friction drive apparatusV of the; present invention;

FIG. 4 is a plan View, partly in section, of another form of a friction driveapparatus constructed in accordance withthe present invention and incorporating a worm gear torque converting mechanism;

FIG. 5 is a plan view, partly in section, of'another form of a friction drive apparatus constructedin accordance with lthe present invention and .incorporating a thrustlimiting device which includes an axially slidable helical gear;

FIG. 6 is a plan View, partlyin section, of another form of a friction drive apparatus constructed in accordance with the present invention and incorporating a thrustlimiting device whichincludes an axially movable Worm drive shaft;

` FIG. 7 is a fragmentary elevation view of a third form v of a control mechanism which can be utilized with various forms of thefriction'drive apparatus of the present invention;

FIG. `8 is an end end elvation view in section `of one form of a deck assembly which may beutilized in the friction drive apparatus of the present invention;

FIG. 9 is an elevation View of another formof a deck assembly;V

FIG. 10 is a bottom plan view of the deck assembly illustrated in FIG. 9;

'FIG/l1 is a ltop plan view of a rollring arrangement incorporated in a deck assembly illustrated in FIG. l2;

FIG.:12 is an elevation view of another form of a deck assembly which may be utilized iny the. friction drive apparatus of the present invention;;

FIG. 13 is a top plan View of a deck -member incorporated in the deck assembly illustrated in FIG. 12;

FIG. 14 is afragrnentary'view in side elevation of another form of a control mechanism, which is especially adapted for'use with the deck assemblyV illustrated in FIG. .12;

FIG. 15 is a plan view,` taken substantially along the line indicated by the arrows 15-15 in FIG. 17, of another formof. a friction drive `apparatus constructed in accordance with the present invention and incorporating a screwl spindle and nut torque converting mechanism;

`FIG.16 is a plan view, partly in section, of the friction drivev apparatus illustrated in FIG. 17;

FIG. 17 is an elevation view taken substantially along l theY line indicated lby the arrows l17-3i7in FIG. 16; and

' 22 and a torque multiplying and converting mechanism v 23both mounted within an outer frame or housing 24E..

The rollring mechanism 22 is `basically `the same asv thatl illustrated and described in the co-pending application of Joseph M. Davin and Hans A. Hug, Serial No. 841, filed January 6, 1960, and reference may be had to this application for det-ails'of the structural features and mode Aof operation of the rollring mechanism.

As illustrated in FIG. 1, the rollringr drive mechanism 22 comprises a pair of parallel disposed shafts 26 and 27 which include complemental but oppositely arranged conical portions. Thus, the large diameter end of the conical portion of the shaft 26 is immediately adjacent the small diameter end of the conical portion of the shaft 27, and vice versa. The shafts are journalled for rotation within bearings 28, 29, 31 and 32. The bearing 28 is supported from the base of the frame 24 while the .bearings 29 and 31 are mounted within suitable openings formed in a web 33 extending across the interior =of the frame 24. However, the bearing 32 is adapted to be shiftable to a limited extent by a coiled compression spring 34 to bias the conical shaft 27 toward the shaft 26 for a purpose which will become apparent hereinafter.

Each of the shafts 26 and 27 is encircled by respective rollrings 36 and 37, which `are of somewhat larger internal diameter than the maximum diameter of the largest ends yof the conical portions of the shafts 26 and 27. The rollrings 36 and 37 are mounted for rotation in a deck member 39. The portions of the rollrings disposed between the shafts 26 `and 27 are pressed into engagement with one another and with the shafts 26 and 27 by the bias exerted on the bearing 32 by the coiled compression spring l34 noted hereinabove. Thus, the rollring 36 is frictionally engaged with the shaft 26 as indidicated by the reference numeral 41 while the rollring 37 is engaged with the shaft 27 as indicated by the reference numeral 42. The rollrings 36 and 37 .thus comprise drive means interconnecting the shaft 26 for drive with the shaft 27, which in turn is rotated by a suitable prime mover, such :as an electric motor 43.

In this regard it may be noted that drive means other than the rollring arrangement illustrated may be uti- .lized for effecting such drive between the shafts 27 and 26. Thus, by way of example, a double roller could be interposed between the shafts 26 and 27. However, encircling rollrings like the rollrings 36 and 37 are preferred inasmuch as such rollrings enable a quite effective frictional engagement between the shafts and rollrings to be obtained, as pointed out in detail in co-pending application Serial No. 842 noted hereinabove.

The rollrings `are tiltable about an axis X-X passing through the areas of engagement 41 and 42 of the rings with the shafts and are preferably contained within a deck member or housing 39.

Various forms of a deck member or housing may be utilized in the friction drive apparatus illustrated in FIG. 1 as well as in different forms `of the friction drive apparatus to be described hereinafter with reference to other figures of the drawings. Three different forms of the deck member `or housing are illustrated in respective FIGS. 8, 9 and 12 wherein like reference numerals designate like parts. lIn FIG. 8 there is illustrated in sectional elevation one specific form of a deck member construction which can be utilized in the drive mechanism of FIG. l. Thus, the deck member 39 may be formed with an enlarged central opening 46 adapted to receive the rollrings 36 and 37 therein. The rollring 36 may preferably comprise .a double flanged peripheral construction, of which one flange 47 is illustrated in FIG. 8. .The width of the rollring 37 is such that the rollring 37 is receivable between the flanges of the rollring 36 to thereby insure accurate axial alignment of the rollrings with respect to one aonther. The deck member 39 may also preferably include flanged roller guide memibers 48 mounted for rotation within recesses formed in the corners of the deck member 39. In this manner, the rollrings and deck member are adapted to be tilted as a unit about the axis X-X passing through the areas of engagement 4-1 and 42 with the shafts 26 and 27. The deck member 39 may also include a pivot pin 49 mounted for rotation within a bearing 51. A second pin or stud member 52 may be ailixed to the deck member 39 on the axis of tilt X-X and at the end opposite that mounting the pivot pin 49. This deck member construction is the same as that illustrated and described in greater Idetail in co-pending application Serial No. 841 noted hereinabove, land, as pointed out in that application, the pin or stud 52 facilitates the connection yof tilt control mechanism to the deck member 39. i

In FIGS. 9 .and l0 there is illustrated another form of a deck housing assembly which may be utilized in the various forms of the friction driveapparatus of the present invention. As illustrated in FIGS. 9 and 10 a deck member 39 is formed with an enlarged circularshaped opening 56 in one portion thereof and a second circular-shaped opening 60 in another portion thereof. The deck member 39 is also formed with an opening 55 which forms a throat interconnecting the circular openings 50 and 60. The diameter of the opening 60 is somewhat larger than the largest external diameter of a flanged rollring 36 so that the rollring 36 may be positioned within the opening 50 and thereafter shifted toward the -throat v55, whereupon the flanges 47 are engaged with and are slidable on the opposed laterally extending surfaces of the deck member 39, as illustrated in FIGS. 9 and l0. The diameter of the opening 60 is however substantially the same as the external diameter of the rollring 37. End plates 25 are suitably ailixed to the deck member 39, as by the socket head bolts and elastic stop nuts illustrated, and serve to maintain the rollring 37 in lateral alignment within the deck member 39. Thus, with the double-flanged rollring 36 shifted to the .position illustrated in FIGS. 9 and 10, the portion of the rollring 37 opposite that engaged by the end plates 25 is interlocked between the flanges 47 of the rollring 36. vIn this manner, the peripheries of the rollrings 36 and 37 may be fricti-onally engaged with one another within the throat 55 and the rollrings and deck member 39 are tiltable as 4a unitary assembly about the axis X-X. For facilitating such tilting of the rollrings and deck member 39 a lever member 3i) is suitably affixed to the deck member 39 as by bolts 35.

In FIGS. ll-l3 there is illustrated another form of a deck housing assembly constructed in accordance with the present invention. In this form of the deck housing assembly, the doubledlanged rollring 36 is adapted to interlock with a rollring 37, as best illustrated in FIG. ll. In this instance a quite simplified deck mechanism 39 is formed with a pair of arcuate-shaped flanges 65 which are Vadapted to engage the opposed lateral surfaces of the rollring 37 on the lower part thereof in the manner illustrated in FIG. 12. The deck member 39 also is formed with an arcuate recess 70 in the upper surface of one end thereof, and this end of the deck member 39 is adapted to be received between the flanges 47 of the rollring 36. A ilexure member 30 is suitably attached to the deck member 39' for facilitating tilting of the rollrings and deck meinber 39 about lthe axis X-X illustrated in FIG. l2.

With general reference to FIGS. 8, 9 and l2, it may be noted that the rollrings and deck housing assemblies may be tilted about the axis X-X by forces applied to the upper `or lower or even the side portions of the deck members 39. Thus, flexibility in the mounting and attachment of the various forms of control mechanisms of the friction drive apparatus of the present invention is thereby achieved.

The speed of rotation of the shaft 26 is dependent upon the axial position of the rollrings and deck member 39 on the conical portions of the shafts 26 and 27. In FIG. l the rollrings and deck member are illustrated in a neutral position wherein the rollrings are disposed midway between the ends of the conical portions. In this neutral 7 Vposition the rollrings 36 and 37 act through equal radii 26K and 27K with respect to the center lines of the shafts 26 and 27 so that the shaft26 is rotated at the same speed asy the shaft 27. As will become more apparent hereinafter, in the neutral position the rollring drive mechanism does not yield any axial output of an output member 72,

which output member forms a part of the torque converting mechanism 23.

So long `as the deck 39 and the rollrings 36 and 37 ar maintained perpendicular to a plane passing through the centerlinesof the shafts 26 and 27, the areas of engagement of the rollrings with the shafts traverse a circular path about the periphery of the conical portions of the shafts. Thus, with the rollrings 36 and 37 in the ,neutral position illustrated in FIG. 1, the shafts-26 and 27. rotate at the same speed. However, should the deck member 39 and the rollrings 36 and 37 be tilted about the axis X-X passing 'through the areas of engagement of the rollrings and the shafts, the areas of engagement ofthe rollrings with the shafts are caused to traverse helical paths on the conical portions of the shafts 26and 27, and the rollrings and deck member 39 are moved axially of the shafts to thereby vary the relative rotational speeds of the two shafts.'

Any suitable'apparatus may be utilized for effecting such i tilting ofthe rollrings and deck member. In FIG. l a control mechanism 56 for accomplishing such -tilting is schematically illustrated. Such control mechanism 56 includes both an actuator S7, which may be of an electrical, pneumatic, mechanical or hydraulic nature, and linkage means 58 interconnecting the deck member 39 and the actuator 57.` Any one of the several forms of control mechanisms illustrated in FIGS. l, 3, 7 and 14 may be incorporated in the friction drive apparatus illustrated in FIG. l, and details of the construction of the control mechanisms illustrated in FIGS. l, 3, 7 and 14,` as well as the manner in form of the invention illustrated in FIG. 1 the means for accomplishing this result comprise the mechanism 23 noted generally hereinabove and include planetary gear means 6l and a power screw 62. As illustrated in FIG. l, a sun'.`

gear 63 is xed for rotation'with the shaft 26 `while a planet gear carrier housing 64 is geared for rotation with the shaft 27 That is, the housing 64 is provided with an external gear 6d disposed inmeshing engagement with a spur gear 65 `mounted on the outboard end of the shaft 27. Planet gears ed, carried by the carrier 64, mesh with the sun gear 63 and a ring gear 67.` The ring gear 67 is formed-integrally with a rotatable shell 68, which is journalled for rotation within one end of the frame 24 Aby bearings 69. The shell 68 includes a radially inwardly extending web '7l having screw threads formed on the inner periphery thereof and engageable with complementary threads formed on an output member '72. Theoutput member 72 'is in turn supported for slidable movement i within a bearingv73 mounted in an end `wall of the frame member 24. In the operation of the apparatus thus far described any differential between the speeds 0f rotation y of the output shafts 26 and 27 is effective to impart rotation movement to the ring gear 67 in a direction dependent upon the relationship of the speed of the `shaft 26 to rthat of the shaft 27. Thus, if the speed of the shaft 25 vis 1 greater than that ofthe speed of the shaft 27, the ring gear 67 is rotated in one direction, but if the speed of the shaft 26 is less than that of the speed of rotation of the shaft f 27, the ring gear 67 is rotated in an opposite direction. Of

course,fif the shafts 26 and 27 are rotated atequalspeeds, as is the case when the deck member and rollrmgs are in n 'the neutral positiondescribed hereinabove,the sun and planet gears, ofthe differential gear means 61 rotate within the ring gear 67 at such peripheral speeds that no rotation is imparted to the ring gear 67. It will be recognized that the effect of any rotation imparted to the ring gear 67 by a speed differential between the shafts 26 and 27 will be to multiply the torque ,output of the shafts. Thus, the shafts 26 and V27 may be rotated at relatively high speeds at a low torque to produce a high torque at a relatively low speedin the ringv gear 67.

The high torque thus madexavailable in the ring gear 67 is further multiplied and converted into an axialthrust in the nonrotatable output member 72 through the threaded connection afforded between the shell 63 and the output member 72.

In accordance with the present invention the axial displacementrof l e output member 72 resulting from a speed differential between the shafts 26 yand 27, as transmitted through the planetary'g'ear eiland power screw 62, can be ,controlled as a function of the magnitude of a force initially. imparted yto the deck member 39 by the control mechanism 56. That is, a desired amount of axial movement of the output member-72 can be obtained by selection of the lamount of deck tilting force imparted by the lcontrol mechanism 56, -and various control mechanisms for'accomplishing such a mode of operation will now be described with particular reference to FIGS.V 2, 3, 7 and 14.

In FIGS. 2, 3 and 7 parts which correspond to like parts in FIG. f1 are indicated by the same reference numeralsbut with the addition of the respective suffixes A, 3, and Cf In FIG. '14 the same reference numerals are kused but with the addition'of the prime; mark. Thus, in FIG. 2 the rollring deck member 39A is adapted to be tilted about the `axisX passing through the areas of engagement of the rollrings with theshafts 26A and 27A, by an actuator 57A. The actuator 57A Vmay be electrically,` pneumatically, mechanically, or hydraulically actuated as noted herein-above, and includes a iiexure strip SSA extending from a movable plunger 82 to the top of the decl; member 39A.` Actuator 57A is mounted on a support 83, which is in turn mounted for sliding movement within bearings vS41 'inf the frame 24. The' support 1llris also connected to the deck member 39A by a vilexure `strip 86 sothat-the entire support member 83 and actuator 57A are movable axially with the rollrings and the deck member 39A upon a force being applied bythe plunger 82 through the .ilexure strip 53A to the deck member 39A such as is effective to tiltthe deck member. 39A about theV axis X and cause axial movement of the rollringsand deck member in the manner described hereinabove.

Feed-back means effective to sum up the axial movement of the output member andimpartf a feed-back force to ther deck member 39A land rorllring drive means in opposition tothe initial tilting force applied by the actuator 57A are also. incorporated in the arrangement illustrated yin FIG; 2. Such means comprise a spring 87 which is attached Vat one end to the output member, such as 72, :as indicated by the .legend in;FIG. 2.y At its opposite end the spring 87 is connected to the deck member 39A.

The operation of thecontrol lmechanism and feed-back arrangement illustrated in FIG. 2 is as follows:

Initially the rollrings and deck member 39A are in the neutralposition, which is that. position of the deck member 39A with respect tothe conical portions of the shafts 26A and 27A Vwhich does not yield any axial output of the member72.` In` the forms of the invention thus far described this neutral position is at the midportions of the conical shafts wherein the shafts rotate at equal speeds. However, depending upon the manner-in which such shafts are connected to drive a'torque converting mechanism, it

will be understood that Vsuch neutralV position may be ob- `V tainedat some positionof the `deckmember with respect to the conical shafts wherein the shafts are rotated at some predetermined ratio of speed other than a one-to-one ratio.. ln any event, for any-one friction'drive apparatus,

this neutral position is always the same regardless of the axial displacement which may be assumed by the output member 72. In this neutral position the overall friction drive apparatus 21 is in a state of equilibrium. Subsequently, the actuator 57A is energized to impart a rst or signal force to the deck member 39A effective to tilt the deck member and rollrings about the axis X and cause the rollrings and deck member to move axially of the shafts 26A and 27A, thus producing a differential between the speeds of rotation of the shafts. As a result of such differential between the rotational speeds of the shafts 26A and 27A, the output member 72 (see FIG. 1) is moved axially in the manner described hereinabove. The resultant axial movement of the output member is summed up and developed as a force in the spring 87 which is fed back to the deck member 39A in opposition to the force imparted by the actuator 57A. Therefore, inasmuch as the output member continues to move so long as the shafts 26 and 27 rotate at the different speeds, the feed-back force by the springs S7 is progressively increased and eventually equals the force applied to the deck member 39A by the actuator 57A. As a result, the deck member 39A is tilted to an inclination opposite that initially imparted by the actuator 57A and the rollrings and deck member 39A are caused to move axially along the shafts 26A and 27A and back to the above-described neutral position. Upon the neutral position being obtained, no further axial movement is developed in the output member 72, and the friction drive apparatus comes to rest at a new condition of equilibrium. Thus, it will be observed that the extent of the axial movement is related to the magnitude of the initial deck tilting force applied by the actuator 57A so that any predetermined axial movement of the output member can be obtained by suitable selection of the input signal supplied to the actuator 57A.

Instead of utilizing a control mechanism adapted for axial movement with the rollrings and deck 39, such as the actuator 57A mounted for movement on the sliding support 83 as described hereinabove, in some instances it may be desirable to mount the actuator at a fixed axial location with respect to the shaft 26 and 27, and such an arrangement is illustrated in FIG. 3. Thus, in FIG. 3 the actuator 57B is mounted in any suitable manner on a portion of the frame 24B and incorporates a plunger 82B connected through a flexure strip 58B to the rollring deck member 39B. Also, in the arrangement illustrated in FIG. 3 a force feed-back spring 37B is connected to the rollring deck member 39B for summing up the movement of the output member and applying a force to the deck member in opposition to the force imparted by the actuator 57B through the flexure strip 81B.

In the operation of the control mechanism 56B illustrated in FIG. 3 energization of the actuator 57B is effective to tilt the rollrings and deck member 39B about the axis X, as indicated by the arrows in FIG. 3. Such titling of the deck member causes the rollrings and the deck member 39B to move axially of the shafts 26B and 27B until the deck member is restored to a perpendicular relationship with a plane passing through the center lines of the shafts 26B and 27B. The resultant differential produced in the speeds of rotation of the shafts 26B and 27B develops such an axial displacement in the output member as is effective to develop a force within spring 87B sufficient to override the initial tilting force of the actuator 57 B and cause the rollrings and deck member 39B to return to the neutral position midway ofthe shafts 26B and 27B.

Other control and feed back mechanisms may be utilized with the friction drive apparatus illustrated in FIG. l, and in FIG. 7 there is illustrated a control mechanism 56C which Iutilizes the principles of a proportional triangle servomechanismV described in detail in the abovenoted copending application Serial No. 841. In the arrangement illustrated in FIG. 7 an actuator 57C of a suitable electric, pneumatic, hydraulic, or mechanical type is connected to effect tilting of the rollrings and deck member 39C through a linkage 58C. The linkage 58C is connected at a fixed angle to the deck member 39C but is slidable within a bearing holder 92 which is reciprocated by the actuator 57C. Thus, the reciprocation of the bearing holder 92 by the actuator 57C causes the linkage 58C to act as a lever for tilting the rollrings and deck member 39C in the direction of the arrows about the axis X. As a result of such tilting of the deck member 39C, the rollrings and the deck member and the linkage 53C move axially of the shafts EdC and 27C, whereupon the linkage 58C slides axially within the bearing holder 92 until the perpendicular relationship of the deck member 39C with respect to a plane passing through the center lines of the shafts 26C and 27C and the original inclination of the link 58C is restored. At this new axial position of the rollrings and deck member 39C the shafts 26C and 27C rotate at different speeds and therefore produce an axial displacement in the output member as described in detail with reference to FIG. l. The resulting axial movement of the output member is summed up and applied as a feed-back force through a bell crank 93 to the linkage 58C. The force of the spring 87C opposes the force imparted by the actuator 57C and, inasmuch as the spring force progressively increases with increased axial displacement of the output member, the spring force is effective to override the actuator force and cause the rollrings and deck member 39C to return to the neutral position midway of the shafts 26C and 27C after an axial displacement of the output member related to the magnitude of the initial tilting force imparted by the actuator 57C has been obtained.

In FiG. 14 there is illustrated another form of control mechanism. In this instance, the control mechanism is especially adapted to be utilized with the form of the deck housing assembly illustrated in FIGS. 11-13. In FIG. 14 parts which correspond to like parts in the forms of the invention described hereinabove lare designated by like reference numerals, but with the addition of the prime mark in FIG. 14. Thus, the control mechanism 56 includes an actuator 57 and a member 58 extends from the actuator 57' and is connected to one end of a shaft 75. The shaft 75 is in turn attached to the flexure 30' of the deck housing assembly. The shaft 75 is supported for axial movement, as between the positions illustrated by the bold and phantom outlines in FIG. 14, by means of a pair of support flexures 40 which are attached to opposite ends of the shaft 75 and which project upwardly from the casing 24 of the friction drive apparatus. A feed-back spring 87 is attached to the output member of the friction drive apparatus, as indicated by the legend in FIG. 14, and is connected to the shaft '75 at an end of the shaft which is opposite that connected to the member 5S'. Thus, an input force may be exerted on the deck member 39 by the actuator 57 to tilt the deck member and the rollrings about the axis X and thereby achieve an axial displacement of the output member of the overall friction drive apparatus in the manner set forth in detail hereinabove with reference to the control mechanisms illustrated in FIGS. 2, 3, and 7. The resultant movement of the output member is progressively summed up by the feedback spring 87 which ultimately applies a force through the shaft 75 to the deck member 39 suiiicient to cause the rollrings and deck member to return to the neutral position wherein no further axial displacement of the output member occurs.

l l` the sufx D Thus, the friction drive apparatus 2li) comprises a rollring drive mechanism 22D and a torqueconverting mechanism 23D disposed within an outer frame or casing 24D. The rollring drive mechanism 22D includes a pair of shafts 26D and 27D having oppositely aligned conical portions as illustrated and mounted parallel to one another. The shaft 26D is journalled for rotation within a bearing 23D mounted within a web 33D extending across the interior kof the frame 24D, and a bearing SED is also mounted within thefweb 33D for supporting one end of the shaft 27D. Drive means, in the form of a pair of rollrings 36D and 37D, encircle the respective shafts 26D and 27D and are aligned with one another Within a deck member 39D. The rollrings 36D and 37D are frictionally engaged with one another and with the shafts 26D and 27D at areas indicated by the reference numerals 4M) and 42D by reason of a biasing force exerting by a shaft-loading spring 34D on a bearing 32D supporting the end of the shaft 27D opposite that journalled within the bearing 31D. Thus, rotation of the shaft 27D as by an electric motor 43Dcauses rotation of the shaft 26D by reason of the frictional drive afforded by the portions of the rollrings interposed therebetween.

As in the arrangement illustratedin IFIG.V 1, the respective speeds of rotation of the two shafts is dependent upon the axial position of the rollrings and deck member 39D With respect to the shafts, and such axial position can be.

regulated by a control mechanism Sdi) which includes an actuator 57D and a connecting member 58D. The control mechanism 56D may preferably comprise one of the arrangements illustrated in FIGS. 2, 3, or 7, although other means for tilting the rollrings or like drive means may be utilized to effect a differential between the speeds of rotation of the shafts 26D and 2'7 D.

In the arrangement illustrated in FIG. 4 the torque conerting mechanism 23D incorporates a pair of Worms 161 and 162 which mesh with diametrically opposed portions of the periphery of a worm Wheel los; As will become apparent from the description to follow, the worms 101 and 102 rotate in opposite directions and may either cause the center of the worm Wheel 103 to move axially in the direction of the arrow A, remain stationary atthe position illustrated in FIG. 4, or move axially in the direction of the arrow B depending upon whether the speed of rotation of the shaft 26D is greater than, equal to, or`

less than that of the shaft 27D. Such resultant movementof the Worm wheel is imparted to an output member f ille through a stub shaft 1% affixed to the Worm Wheel 193.

The worm lill may be directly connected for rotation with the shaft 26D. Thus, the worm lill may be suitably i mounted at a fixed-axial position on an extension of the shaft 26D by any suitable means. As illustrated in FIG. 4 the end of the shaft 26D opposite that journalled Within the bearing 28D is supported within a bearing lll?.

The worm 102 is adapted to be rotated with and at the same speed as the shaft 27D, and for this purpose the Worm 102 is mounted on a shaft 68 connected for rotation with the shaft 27D through a gear train HB9. The gear train E09 includes a spur gear lil suitably affixed to the shaft 27D, an idler gear M2 mounted on a shaft journalled for rotation Within a bearing il?) mounted within the web 33D, and a third spur gear M5 affixed to Ythe shaft lilS. The pitch diameters of all of these gears are equal so that the shaft 103 rotates at the same speed as the shaft 27D. The shaft 1655 is suitably supported Vfor rotation within bearings M4 and ilo.

The output member 104, notedrhereinabove, may preferably include a pair of guide flanges j eachfof which In the operation of the Afriction rdrive'apparatus 211D illustrated in FlG. 4, adilferential in the speeds of rotaincludes a bearing MS in the outer end thereof and slidf able along the respective shafts 26D and i613. Thus, thel flanges 117 serve as guide means alongwith a bearing 119 in the frame 24D for insuring against tilting or cocking of the output member 104.

tion of the shafts 26D and 27D caused by energization of the control'mechanismSoDand axial movementof the rings andv decl; member 39D from the neutral position illustrated, causes the Worms 10i andxltll to rotate at different speeds and thereby produce translatory movement of the center of the lworm Wheel N3 and the output member 104 in a direction dependent upon the speed of rotation of the shaft ZoDwith respect to the shaft 27D, as noted hereinabove. It will be recognized that the quite large Lmechanical advantage afforded by the Worm gear mechanism enables the torque of the rollring drive mechanism 22 to be greatly multiplied, and the above-described translatory motion of the worm wheel and the output member iti-1- is effective to convert such multiplied torque into an axially directed thrust on a load device connected to the output member ldd. As in the friction drive apparatus illustrated in FIG. 1, the axial movement of the output member 194 may be summed up through a feed-back mechanism, such as that illustratedin FIGS. 2, 3, and 7 and applied in conjunction with `the control mechanism 56D to effect a controlled movement of the output member ille. Y

In the 4friction drive apparatus described hereinabove the actual thrust produced within the output member is dependent upon the resistance to axial movement offered by the load device to which the output member is connected. While a lquite largeV output thrust can be obtained-from a rollring drive mechanism which itself develops only a smalljoutput torque, the maximum available thrust of the output member is, in the final analysis, dependent upon the maximum torque which can be developed by the rollring drive mechanism.` Thus, if the output member of the Ifriction vdrive apparatus should be required to overcome an external resistance exceeding the maximum available thrust of the frictiondrive apparatus as determined by thek maximum :torque output of the rollring drive mechanism, such as might happen upon a load device become stuck or locked-up in the course of operation,v a condition of slip of the rollrings on the conical peripheries of the shafts can occur. Such slippage can )cause considerable damage to the cones.

In accordance with the present `invention means are l preferably included in the'friction drive apparatus for sensing the ymagnitude ofthe thrust developed by the friction drive apparatus and applying a force lto the rollringszand deck member, or other drive means, effective to cause the rollring drive mechanism to return to ya neutral position midway of the shafts 26D and 27D `the component parts of the friction driveV apparatus illustrated in FIG. 5 is like that of the friction drive apparatus illustrated in FIG. 4,*witl1 the exception of the kdrive between the shaftZE and theshaft NSE now to be described.

In the yfriction drive apparatus ZlElillustrated in FIG. 5 a helical gear 121 isxed for rotation with a shaft 27E but is axially slidable thereon. Thus, splines Yor other `similar structure, notfill'ustrated, may be utilized for rotating the gear V121 with the shaft 27E. The gear 121 lmeshes with a gear 122, drivenby the electric .motor 43E and the gear 122m turn meshes with a gear MSE fixed for rotation with the `shaft' WSE. The' pitch diameters of the gearsll, 122, and I1-3E are equal so that the shaft MSE and worm lilfiE rotate at the same speed as the shaft 127B rIhe means affording the connection ,described hereinabove.

between the gear 11315I and the shaft 111515 preferably include a clutch 123 comprising an outer housing 124i rigidly-affixed to the gear`113E and mounting a band or clutch 'fac-ing 126 therein. A second clutch'facing or band 127 is mounted on the shaft 158B and engaged with the facing 126. Thus, the slip clutch 123 enables the gear 113E to slip with respect to the shaft 16513 under certain conditions of operation.

As noted hereinabove, the helical gear 121 is movable axially with respect to the shaft 27E. Normally the helical gear 121 is retained at a selected location on the shaft 27E as by a pair 0f pre-loaded springs 128 and 129; however, other apparatus can be utilized for this o purpose if desired. Thus, a ball and detent mechanism 130 in conjunction with springs 128 and 129 can equally well be utilized.

It is a characteristic of helical gears, as contrasted to ordinary spur gears, that the inclined faces presented by .the gear teeth enable an axial thrust to be developed on the gear as a function of the torque transmitted by the gear. Advantage is taken of this characteristic in the arrangement .illustrated in FIG. for sensing the development of an output thrust in the output member MME approaching that critical thrust which can cause slippage of the rings 36E and 37E on the conical surfaces of the shafts 26E and 27E. Thus, as the output thrust of the output member 104B builds up, due to an external resist-ance presented by the load dev-ice, the torque transmitted by the shafts 108B and 26E .increases and causes acer-responding increase in the torque transmitted by the helical gear 121. Under normal circumstances the torque build-up is insufficient to cause significant axial movement of the gear 121 from the position illustrated Lin FIG. 5. However, if the output thrust `should exoecd a predetermined magnitude, the helical gear 121 is shifted against the bias exerted by the pre-load springs 128 and 129 and ball and detent mechanism 13@ to a position wherein the helical gear contacts a shiftable fork 131 which is in turn connected to the deck member 39E. As illustrated in FIG. 5, the shiftable fork 131 is connected to the deck member 39E in the same manner as that of the displacement summing feed-back spring 87E Thus, the shiftable fork 131, when engaged and moved by the helical gear 121, exerts a force on a deck member 39E in opposition to the initial tilting force imparted by the actuator 57E. As a result, the interaction between the helical gear 121 and the shiftable fork 131 is effective to cause the rollrings and deck member 39E to return to the neutral position midway of the conical portions of the shafts 26E and 27E to thereby limit the thrust output of the output member 104B at a predetermined level less than that which can cause slippageof the rollrings on the conical portions of the shafts 26E and 27E. Such action .is obtained even though the output member 164B has not reached an axial displacement suicient to develop a feed-back force in the spring 87E sufficient to return the rollrings and deck member 39E to the neutral position. While it can be assumed that the shiftable fork 131 tilts the deck member 39E almost instantaneously, some time will elapse until the deck member 39E has completed its follow-up to thefneutral position. Dur-ing this followup period, the angular velocities of worms IME and 102B are not identical, so that output member 104B -is urged to travel still further or if the output member is prevented from doing this, there is a build up of a torque level' in the rings which would cause them to slip. A

` slip clutch mechanism 123 Iis used to equalize the angular velocities of Worms 101B and 102B during this follow up of the deck member 39E.

Thereafter, it will be recognized that a signal calling for movement of the output member away from the blocked condition can be introduced in the control mechanism 56E.

In FIG. 6 there is illustrated another embodiment of a friction drive apparatus constructed in accordance with 14 Y the present invention and incorporating means for limiting the output thrust of the friction drive apparatus. The apparatus illustrated in FIG. 6 is generally similar in construction and mode of operation to that illustrated and described in FIGS. 4 and 5, and like reference numerals, but with the addition of the suffix F, are utilized to designate like parts. f

In the friction drive apparatus 21E illustrated in FIG. 6 a shaft 2'7F is connected for drive -by the motor 43F through gears 141 and 142. At one end the shaft 27F is journalled for rotation within a bear-ing 32F, which may be spring-loaded like the bearings 32D and 32E i1- lustrated `in FIGS. 4 and 5. The opposite end of the sha-ft 2'7F may be suitably supported in bearing structure not illustrated in FIG. 6, and a gear 143 is fixed for rotation lwith the shaft 271:. The gear 143 meshes with an idler 'gear 144 which in turn meshes with a gear 146 fixed for rotation with the shaft 10SF mounting the worm 192B The Width of the gear 146 is -suicient to enable a limited amount of sliding movement of the shaft 11G/3F to be obtained while the gears 144 and 146 are maintained in meshing relation.

The worm 11111?, like the worm 101D and 1MB i1- lustrated in FIGS. 4 and 5, is mounted on the shaft 261? so as to be rotated at the same speed as the shaft 26F. Thus, the worm 1022 rotates at the same speed'as the shaft 27F while the worm 11911J rotates at the same speed as the shaft 26F, and any difference in the speeds of rotation of the two shafts causes translatory motion ofthe center of the worm.wheel 103F and output member )NMF to be obtained.

Thrust-limiting means, indicated generally by the reference numeral 151 and including a fork member 152, are included in the friction drive apparatus 21F. The fork member 152 is mounted for pivotal movement about a fixed fulcrum 153 disposed intermediate the ends thereof and is connected at one end through a lost-motionlconnection 154 to a 4depending lug 150 affixed to the connect- .ing member 58E The opposite end of the fork member 152 is connected for laxial movement'with the shaft 108]? by a link member 155.

Axial movement of the shaft 10813 is effective to pivot the fork member 152 about the fulcrum 153 and into engagement with the leg of the connection member 583? and is permitted by reason of a preloaded spring biasing .construction acting on the end of the shaft MSF opposite that supported Within the bearing 11d-F. Thus, a bearing 156 is retained in fixed axial position on the shaft ltSF as by a pair of snap rings 157 seated within suitable grooves formed on the shaft. The bearing 156 vis in turn biased toV the normal position illustrated in FIG. 6 as by Bellville spring stacks 158 and 159 acting on the opposite faces thereof and seated against suitable seat structure formed in or attached to the frame 24F.

In the operation of the friction drive apparatus illustrated in FIG. 6 the output thrust developed by the output member MMF i-s transmitted through the shaft NSF and bearing 156 to a respective .spring stack 158 or 159, depending upon the direction in which the output thrust is exerted 'by the output member. If the resistance offered by the load device to which the output-member 164F is connected should approach that which can cause slippage of the rollrings on the conical portions of the -shafts ZrrF and 27F, the reaction thrust developed in the shaft MSF becomes large enough to compress the corresponding spring stack158 or 159 an amount suficient to pivot the fork member 152 about the fulcrum 153 and into engagement with the leg 150 of the connecting member ESF. Upon such pivoting of the fork member 152 being obtained, connecting member .5a-8F forces deck member 39F Vto be tilted at an angle which effect-s axial movement of the rollrings and deck member to the neutral position midway of the conical portions of the shafts 26F .and 27F, whereby further axial movement or increased thrust in the output member 10ft-F is prevented.

In FIGS. 15-1S there is illustrated another form of a its friction drive apparatus constructed in accordance with the presentvinvention .and incorporating a quite simple Y screw spindle and nut mechanism for converting a dilferential betweenthe speeds of rotation of a -nair of rotary shafts into an axially directed thrust. In FIGS.VV 15,-18 parts which generally correspond to like parts in the friction drive apparatus illustrated in FIGS. 1 and 4-6 `are indicated by like reference numerals but with `the addition of the suffix G.

Thus, and with particular reference to FIG. 16, a friction drive app-aratus is indicatedV generally by the reference numeral 21G and includes a housing or frame MG. In this instance, the housing maypreferably includea lower section 24G fitted with a mating upper section 24G' (see FIG. 17)` so that the rollring drive mechanism 22G and torque converting mechanism 23G is completely enclosed therein.

The rollring drive mechanism 22G is basically like that described in the various forms of the friction drive mechanism illustrated in the respective FIGS. l 'and 4-6.

Thus, the drive mechanism 22G includes a pair of parallel shafts 266 and 27G having oppositely disposed conical portions encircled by respective rollrings 36G and SWG. The rolln'ngs are mounted for rotation within a deck member 39S, which may be like those illustrated in FIGS. 8-13, as described hereinabove. The inner peripheries lofthe portions ofthe rollrings disposed between the shafts are engaged with the shafts, as indicated bythe reference numerals 41G and42G, so as to afford a friction-drive between the shafts.l

As in the other embodiment-s of the present invention, the shaft A27'G is movable to a limited degree toward and away from-the shaft 26G, and suitable bias-ing means are provided for maintaining rm frictional engagement `between the shafts and the portions of the Yrollrings inter.- posed therebetween. With particular reference to FIGS. 10 and l2, itis seen that one end of the shaft 27G is journal'led for rotation within ya be-aring 31G which, in turn,

is mounted in a fixed position within a web SEG extend-y V202 formed yin one end of the casing 24G so as to be slidable therein. With particular` reference to FIG. 18, it is seen ythat a bracket V203 is formed on the interior of the casing 24Gand a bolt 204 extends through suitable openings forrned in the bracket 2433 and the frame 201.V Also, a corner portion-of the frame 201 is recessed to forma platform 2% `which affordsa seat fora stack ofBelleville springs B4G or the likeinterposed between thehead of the bolt 204 yand the frame 2G11. Thus, by turning down a nut 2(27 the spring stack 34G is compressed to exert a force through the bearing 32G on the shaft 27G to bias the shaft- 27G toward the shaft 25@ and thereby main-` tain the rollrings 36G andV 3'7G in firm frictional engagement `with the conical portions of the respective shafts K 26G and 27G.

` .across the interior of the casing 24G, `and the web is effective to seal off the drive mechanism 22G from the torqueconverting mechanism` 23G to thereby prevent any lubri- .cant from the torque-converting mechanlsm from conta-minating the control mechanism or other operating parts of the drive mechanism.

In this instance, the shaft26G'is connected for directr drive by a suitable prime mover, such as an electric motor The thrust bearing 28G'is thus mounted MG.. Rotation of the shaft 25G by the motor 3G frictionally .drives the `shaft 27G throughthe rollrings engaged therewith, and thel speed lof rotation of the shaft 27G with respect to the shaft 26G is dependent upon the axial position` of the rollrings and deck member 39G alongV conical shafts, asin the `other forms of the present invention. Thus, the shaft 27G may-be rotated slower than, at the same Vspeed as, or faster thanthe shaft 26G depending upon the position `of the rollrings `and deck member 39G with respect to the conical portions of the shafts, and such positioning `ofthe rollrings and deck member SeG is readily obtained by tilting the rollrings `and deck member about the .axis X-X by control mechanism presentlyv vto be described.

In accordance with the present invention, the portion of the shaft 26G which extends between the web `213 and the end wall of the casing 24G is formed with an external thread so as to afford a screw spindle 216. A nut 217 is threaded on the screw spindle 216 andis formed with a circumferentialfrow of gear teeth 218 Vdisposed betweenradially extending flanges 219. A gear 221 is mounted on the portion of the shaft 27G extending between'the web 213 andthe end wall *of the casing 24G and meshes with the gear teeth 213 between the flanges 219.' The gear 221 is slidableaxially on the shaft 27G but is suitably fixed for rotation therewith as by aV pin 223 slideable Within a'slotted guideway 24 formed in the shaft 27C'. From the foregoing it will be apparent that the nut 217 is adapted to be rotated in the same direction asthe screw spindle 216 by reason'of ythe geareddrive connection to the shaftZ'iG.` The pitch diameters of the gear teeth of the gear v221 and the-.nut 217 are Hequal so that the nut 217 rotates at the same angular Y speeds, the nut 217 iis ycaused to move axially on the screw spindle 216 'in a direction dependent upon the Vspeed of rotation lof the shaft 27G with respect to the shaft 26G.

The friction drive vapparatus 21G, includes means for transmitting such axial-movement ofthe nut 217 toan output member on the exterior of the casing 24G. Thus, a housing 226 is connected to the nut 217 for axial movement therewith by a ball bearing 227 "interposed therebetween. An output shaft 72G projects from a face of the housing 226 and is slidable within a bushing 228 mounted within ari-opening in an endl wall of the casing 24G l(see FIG. 17). The outermost end of the output shaft 72Gis connected to a crosspiece 229, and a second shaft 231 is attached to the. crosspiecev and isrslidable within a suitable guideway formed within the end wall of the casing MG. Thus, the double-shaft' arrangement afforded by the shaft '72G and 231 minimizes any tendency of the crosspiece 229 to cant and therebyv bind the output shaft 72G.. The crosspiece 229 may include any suitable structure for facilitating itsv connection to a load device.

In FIGS. l5 and 17 there is illustrated a preferred form of a control mechanism for positioning `,the rollrings Vand deck member SSG axiallyof the conical portions of the Vshafts 26G and 27G to achieve the desired differcntial between` thegspeedsl of rotation of the shafts. Such control mechanism is indicated generally by the reference numeral 56G in FIGS. l5 vand 17 and includes an actuator S'G. As in the other forms of the present invention the actuator 5713v may beof any'suitable' electrical, hydraulic, pneumatic, or mechanical type and includes a member SSG which is movable towardand away from the actuator 57G in response to a `control signal applied tothe actuator. In this instance, however, the member` SSG is not directly connected to the deck rnember 39G, but is instead connected to a summing bar 231 adjacent `one end thereof. The summing bar 231 is in turn connected to the deck member 396 by'a Wire rod 232 (see FIG. Thus, as illustrated in FIG. 17, a bar 23) projects upwardly from deck member 39S within a bellows-type of seal 235 and the wire rod 232 is attached to the upper end of the bar 230. A liexure strip 233 connects an end of the summing bar 231 to the casing 24G and affords a fulcrum for pivoting movement of the summing bar about the point of connection to the iiexure strip 233.

A feed-back spring 87G is connected to the housing 226, and thus, the output member, and is also connected to the summing bar 231 intermediate the rod 232 and the exure strip 233. It may be noted that the feed-back spring 87G is contained within a tube 236 which is attached at one end to an upwardly projecting flange 226F of the housing 226. The end of the tube 236 opposite that attached to the ange 226F is slidably disposed Within an opening 237 extending through the web 213. The opening 237 is formed with an annular recess in the inner surface thereof, and a suitable seal 238 is disposed therein so as to prevent any seepage of lubricant from the torque-converting mechanism 23G to the area of the control mechanism 56G.

To facilitate initial alignment of the summing bar 231 a trimmer spring 241 is included in the control mechanism 56G. With particular reference to FIG. l5, it is seen that one end of the trimmer spring 241 is seated on an end portion of the summing bar 231 farthest from the fulcrum afforded by the llexure strip 233. The opposite end of the trimmer spring 241 is seated on a suitable spring seat 242 mounted on the casing 24G. From the relative dispositions of the feed-back spring 87G and the trimmer spring 241 illustrated in FIG. 15, it will be apparent that the compressive force exerted by the trimmer spring 241 opposes the tension force exerted by the feed-back spring S'IG on the summing bar 231. Thus, by providing for suitable adjustment of the spring seat 242 the force exerted by the trimmer spring 241 can be adjusted to counteract any tendency toward initial unbalance developed by the feed-back spring S7G. Thus, the trimmer spring enables the initial alignment of the summing bar 231 to be readily obtained.

To summarize the operation of the friction drive apparatus illustrated in FIGS. 15-l8, the force of the trimmer spring 241 is adjusted to obtain the initial alignment of the summing bar 231 which is effective to maintain the rollrings and deck member 39G in the neutral position wherein the shafts 26G and 27G are rotated at the same angular velocities. In this condition the nut 217 rotates at the same speed as and at a fixed axial position on the screw spindle 216 so that there is no axial movement of the output member 72G. Thereafter an input signal of the desired polarity and magnitude is applied to the actuator 57G to pivot the summing bar 231 about the fulcrum afforded by the flexure spring 233, whereupon the deck member 39G is tilted and is caused to move axially on the conical portions of the shafts 26G and 27G to vary the speeds 0f rotation of the shafts. The resulting differential in the speeds of rotation of the shafts develops a like differential between the speeds of rotation of the nut 217 and the screw spindle 216 causing the nut 217 to move axially on the screw spindle 216. By reason of the large mechanical advantage obtained by the low pitch of the threads of the screw spindle an axial thrust of quite large magnitude is made available in the nut even though the torque of the shaft 27G is relatively small. The axial movement of the nut 217 is summed up by the feed-back spring 87G and applied to the summing bar 231 in opposition to the force imparted to the summing bar through the exure piece SSG by the actuator 57G. The force of the feed-back spring 87G progressively builds up and is ultimately effective to move the summing bar 231 in a direction to cause the deck member 39G to return to the neutral position wherein the shafts 26G and 27G again rotate at the same speed. Thus, the amount of axial movement of the output member 72G is controlled in accord- Cit 1S ance with the magnitude of the input signal applied to the actuator S7G.

Thus, in accordance with this invention a friction drive apparatus incorporating conical elements rotated at relatively high speed but low torque is effective to develop a quite large axial thrust in a mechanism of minimum overall dimension. Also, the axial movement of the output member can be regulated as a function of an input signal applied to the friction drive apparatus so that the friction drive apparatus automatically obtains a state of equilibrium upon the desired axial movement of the output member being completed. Furthermore, the present invention enables the output thrust developed by the friction drive apparatus to be continuously sensed or monitored and incorporates mechanism for automatically limiting theV output thrust to prevent internal damage to the friction drive apparatus in the event that the load device to which the friction drive apparatus is connected should present an unexpectedly high resistance.

Thus, while we have illustrated and described the preferred embodiments of our invention, it is to be understood that these are capable of variation and modification, and we therefore to do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.

We claim:

1. In a friction drive apparatus of the kind in which a pair of complemental and oppositely contoured conical shafts are disposed parallel to one another and are interconnected for rotation with one another by drive means engaged with the adjacent surfaces of said shafts and wherein said drive means are tiltable about the areas of engagement with said shafts during rotation of said shafts to cause said drive means to move axially of said shafts and thereby vary the relative rotational speeds of said shafts, torque-converting means for converting a differential between the respective speeds of rotation of said shafts into an output thrust, said torque-converting means including counter-rotating members connected for drive by said conical shafts. v

2. In a friction drive apparatus of the kind in which a pair of complemental and oppositelyY contoured conical shafts are disposed parallel to one anotherand are interconnected for rotation with one another by drive means engaged with the adjacent surfaces of said shafts and wherein said drive means are tiltable about the areas of engagement with said shafts during rotation of said shafts to cause said drive means to move axially of said shafts and thereby vary the relative rotational speeds of said shafts, torque-converting means for converting a differential between the respective speeds of rotation of said shafts into an output thrust, said torque-converting means including planetary gear means connected for rotation by said shafts and effective to multiply a torque developed by a differential between the respective speeds of rotation of said shafts.

3. A friction drive apparatus comprising a pair of complemental and oppositely contoured conical shafts disposed parallel to one another, drive means engaged with the adjacent surfaces of said shafts and interconnecting said shafts for rotation with one another, means for tilting said drive means about the areas of engagement with said shafts during rotation of said shafts to cause said drive means to move axially of said shafts and thereby vary the relative rotational speeds of said shafts, and torque converting means for developing a torque in response to a differential between the respective speeds of rotation of said shafts, said torque converting means comprising worm gear means including both rst and second worms connected for rotation with respective ones of said shafts and a worm wheel meshing with said iirst and second worms at diametrically opposed portions thereof and posed parallel to one another, drive means engaged with Y the adjacent surfaces of said shafts and interconnecting said shafts for rotation with one another, control means f for tilting said drive means about the areas ofy engagement with said shafts rduring rotation of said shafts to cause saidfdrive means to move axially of said shafts and thereby vary the relative rotational speeds of said shafts, and torque-converting means for converting a .dilerential between the speedsof rotation of said shafts into an 4output thrust, said torque-converting means including a screw spindledirectly driven by fone of said shafts, a nut threaded on said screw spindle, and a drive connection between said nut andthe other of said shafts.

5. In friction drive apparatus of lthe kind in which a pair of complemental and oppositely contoured conical shafts are disposed parallel to one another and are interconnected for rotation with one another by drive means engaged with the adjacentsurfaces of said shafts such that power supplied toone of said shafts causes rotation of both of said shafts and whereinsaid drive means are tiltable about the areas of engagement with said shafts from a neutral position, inwhichneutral position said drive means traverse a circular path on the peripheries of said shafts at predetermined axial positions thereon and said shafts rotate at a predetermined ratio of speeds, to an inclined position, wherein said drive means traverseY a helical path on the peripheries of said shafts, to cause said drive means to move axially of said shafts away from said neutral position and thereby vary the relative rotational speeds of said shafts; control means associated with said drivevmeans for imparting a first force to said drive kmeans to achieve a selected amount of tilt of said drive means; torque-converting means driven by said shafts for converting a differential between 'the` respective speeds of rotation `of said shafts into an output put member .which is movable axially for transmitting the thrust to a load device; and feed-back means effective to sum up the axial movement of said output'member and apply a second force to said drivey means `in opposition to said rst force to returnthe drive means to said neutral position.

6. A friction drive apparatus as defined in claim wherein said control means are mounted at a fixed axial position with respect to said shafts. v

7. A friction drive apparatus as rdefined :in claim 5 wherein said control means are mounted for axial movement with said drive means.

8. In friction drive apparatus of the kind in which a pair of complemental and oppositely contoured conical shafts are disposed-parallel to one another and are interconnected for rotation with one another by drive means engaged with the adjacent surfaces of said shafts such that power supplied to one of said shafts causes rotationof both of said shafts and whereinsaid drive means are tiltable about the .areas of engagement with said shafts from a neutral position, in which neutral position: said drive means traverse a circular path on the peripheries of said shafts at predetermined axial positions thereon and said shafts rotate at a predetermined ratio of speeds, to an inclined position, wherein said drive means traverse a helical path on thev peripheries of said shafts, to cause said drive means to move axially of said shafts and away s from said neutral position and thereby vary the relative rotational speeds 4of said shafts: controlA means associated with said drive means for imparting a firstforcefto said drive means to achieve a selectedamount of tilt of said drive means; torque-converting means including planetary gear means driven by said shafts for converting a differential between the respective speeds of rotation of said shafts into au output thrust, said torque-converting means also 4including power screw means driven' by said planetary gear means, said power screw means including an output member which is movable axially for transmitting the thrust to a` load device; and feed-back means effective to sum up the axial movement of said output member and apply a second force, of a magnitude dependent upon the extent of the axial movement of said output member, :in opposition to said first force to return the drive means to said neutral position upon Vthevoutput member obtaining an overall displacement related to the magnitude of said first force.

9. In friction drive apparatus of the-kind in. which a pairY of complemental and oppositely contoured conical shafts are disposed parallel to one another and are inter- ,connectedV for rotationwith one` another by drive means l engaged with the adjacent surfaces of said shafts such that Y helical path onthe peripheries of said shafts,tofca.use said drive means to move axially of said shafts away from said neutral position and thereby vary the relative rotational speeds of said shafts; control means associated with said drive means for imparting a first force to said drive means to-achieve a selected amount `of tilt of said drive means; torque-convertingmeansincludinga worm gear having worm members driven by said shafts for converting a differential betweenr the respective speeds of rotation of said shafts into an output thrust, said worm gear including a worm wheel which is movableaxially of said shafts by a difference in the speedsof rotation of said worm members for Vtransmitting the thrust to a load device; and feed-back 'means effective torsum up the axial movement of said worm .wheel and apply a second force to said drive means in oppositiony to saidvrst force to returny the drive ymeans tosaid neutral position.

10. In a friction drive apparatus of the kind in which a pair of complemental and oppositely contoured conical shafts are disposed parallel to oneV another and are interconnected for yrotation with one another by drive means engaged with'the adjacent surfaces of said shafts such that power supplied to one of saidshafts causes rotation of both of said shafts and wherein said drive means are tiltable labout the areas of engagement-with said shafts from -aneutralpositiom in which neutral position said drive means traverse a circular path on the peripheries of said shafts at predetermined axial positions thereon and said shafts rotate at a predetermined ratio of speeds, to an inclined position, wherein said drive means traverse a helical path on the peripheries of said shafts, to cause said drive means to move axiallyof said shafts away from said neutral position and thereby vary the relative rotational speeds of Vsaid shafts: torque-converting means driven yby said shafts for converting a speed differential between said shafts into an output thrust; and thrustlimiting-means for sensing an output thrust of a predetermined magnitude and applying a force to the drive means effective to return the drive .means to said neutral'position and thereby prevent the development of a thrust in said friction drive apparatus such as would cause slippage between said shafts and drive means.

l1. Av friction drive apparatus as defined in claim 10 wherein said torque-converting means include a shaft vmember movable; axially against a resilient. bias by an output thrust of a predetermined magnitude and-wherein said thrust limiting means include a fork member shiftable by axial movement'of said shaft memberand connected to said drive means through a lost-motion connection so that said forkV member isnorrnally spaced from said drive means but isv engageable therewith upon the 21 development of said predetermined thrust to impart a force to said drive means effective to cause said drive means to return to said neutral position.

12. A friction drive apparatus as defined in claim 10 wherein gear means interconnect said torque-converting means for drive by one of said shafts, said gear means including a helical gear which is slidable axially upon an output thrust of a predetermined magnitude being developed in said torque-converting means and wherein a fork member is connected by a lost-motion connection to the helical gear and effective to apply a force to the drive means to return the drive means to said neutral position upon said predetermined magnitude of output thrust being obtained.

13. A friction drive apparatus of the kind in which a pair of complemental and oppositely contoured conical shafts are disposed parallel to one another and are interconnected for rotation with one another by drive means engaged with the adjacent surfaces of said shafts such that power supplied to one of said shafts causes rotation of both of said shafts and wherein said drive means are tiltable about the areas of engagement with said shafts from a neutral position, in which neutral position said drive means traverse a circular path on the peripheries of said shafts at predetermined axial positions thereon and said shafts rotate at a predetermined ratio of speeds, to an inclined position, wherein said drive means traverse a helical path on the peripheries of said shafts, to cause said drive means to move axially of said shafts away from said neutral position and thereby vary the relative rotational speeds of said shafts: control means associated with said drive means for imparting a first force to said drive means to achieve a selected amount of tilt of said drive means; torque-converting means driven by said shafts for converting a differential between the respective speeds of rotation of said shafts into an output thrust, said torque-converting means including an axially movable output member for transmitting the output thrust to a load device; feed-back means effective to sum up the axial movement of the output member and apply a second force to said drive means in opposition to said first force to return the drive means to said neutral position; and thrust limiting means for preventing slippage of said drive means on said shafts, said thrust-limiting means being responsive to the thrust developed in said torque-converting means and effective to apply an additional force to said drive means in opposition to said first force to cause the drive means to return to said neutral position upon a predetermined magnitude of thrust being developed in said torque-converting means.

14. In friction drive apparatus of the kind in which a pair of complemental and oppositely contoured conical shafts are disposed parallel to one another and are interconnected for rotation with one another by drive means engaged with the adjacent surfaces of said shafts such that power supplied to one of said shafts causes rotation of both `of said shafts and wherein said drive means are tiltable about the areas of engagement with said shafts from a neutral position, in which neutral position said drive means traverse a circular path on the peripheries of said shafts at predetermined axial positions thereon and said shafts rotate at a predetermined ratio of speeds, to an inclined position, wherein said drive means traverse a helical path on the peripheries of said shafts, to cause said drive means to move axially of said shafts and therehy vary the relative rotational speeds of said shafts: control means associated with said drive means for imparting a first force to said drive means to achieve a selected amount of tilt of said drive means; said control means including an actuator for developing said first force, a summing bar mounted for pivoting movement about an end thereof, a first connection between said actuator and said summing bar, and a second connection between said summing bar and said ldrive means; torque-converting means driven by said shafts for converting a differential between the respective speeds of rotation of said shafts, as developed by such tilting of the drive means into an axially directed thrust, said torque-converting means including an output member which is-movable axially for transmitting the thrust to a load device; and feed-back means effective to sum up the axial movement of said output member and apply a second force proportioned to the extent of the axial movement of said drive means to said summing bar in opposition to said first force to return the drive means to said neutral position upon the output member obtaining an overall displacement related to the magnitude of said first force.

15. A friction drive apparatus as defined in claim 14 including trimmer means connected to said summing bar for adjusting initial alignment of said summing bar t0 position said drive means at said neutral position.

16. A friction drive apparatus comprising a pair of complemental and oppositely contoured conical shafts disposed parallel to one another, drive means engaged with the adjacent surfaces of said shafts and interconnecting said shafts for rotation with one another, said drive means being tiltable about the areas of engagement with said shafts during rotation of said shafts to cause said drive means to move axially of said shafts and thereby vary the relative rotational speeds of said shafts, torque multiplying means for developing a torque in response to a differential between the respective speeds of rotation of said shafts, said torque multiplying means including planetary gear means having a sun gear connected for rotation with one of said shafts, a planet gea-r carrier connected for rotation with the other of said shafts and carrying a plurality of planet gears, and a ring gear engaged by each of said planet gears, and power screw means for converting the torque developed by said torque multiplying means into a thrust directed axially of said shafts, said power screw means being driven by said ring gear and including an output member which is moved axially by rotation of said ring gear.

References Cited in the file of this patent UNITED STATES PATENTS DON A. WAITE, Primary Examiner.

Kashiwara Sept. 27, 1960 

5. IN FRICTION DRIVE APPARATUS OF THE KIND IN WHICH A PAIR OF COMPLEMENTAL AND OPPOSITELY CONTOURED CONICAL SHAFTS ARE DISPOSED PARALLEL TO ONE ANOTHER AND ARE INTERCONNECTED FOR ROTATION WITH ONE ANOTHER BY DRIVE MEANS ENGAGED WITH THE ADJACENT SURFACES OF SAID SHAFTS SUCH THAT POWER SUPPLIED TO ONE OF SAID SHAFTS CAUSES ROTATION OF BOTH OF SAID SHAFTS AND WHEREIN SAID DRIVE MEANS ARE TILTABLE ABOUT THE AREAS OF ENGAGEMENT WITH SAID SHAFTS FROM A NEUTRAL POSITION, IN WHICH NEUTRAL POSITION SAID DRIVE MEANS TRAVERSE A CIRCULAR PATH ON THE PERIPHERIES OF SAID SHAFTS AT PREDETERMINED AXIAL POSITIONAL THEREON AND SAID SHAFTS ROTATE AT A PREDETERMINED RATIO OF SPEEDS, TO AN INCLINED POSITION, WHEREIN SAID DRIVE MEANS TRAVERSE A HELICAL PATH ON THE PERIPHERIES OF SAID SHAFTS, TO CAUSE SAID DRIVE MEANS TO MOVE AXIALLY OF SAID SHAFTS AWAY FROM SAID NEUTRAL POSITION AND THEREBY VARY THE RELATIVE ROTATIONAL SPEEDS OF SAID SHAFTS; CONTROL MEANS ASSOCIATED WITH SAID DRIVE MEANS FOR IMPARTING A FIRST FORCE TO SAID DRIVE MEANS TO ACHIEVE A SELECTED AMOUNT OF TILT OF SAID DRIVE MEANS; TORQUE-CONVERTING MEANS DRIVEN BY SAID SHAFTS FOR CONVERTING A DIFFERENTIAL BETWEEN THE RESPECTIVE SPEEDS OF ROTATION OF SAID SHAFTS INTO AN OUTPUT THRUST, SAID TORQUE-CONVERTING MEANS INCLUDING AN OUTPUT MEMBER WHICH IS MOVABLE AXIALLY FOR TRANSMITTING THE THRUST TO A LOAD DEVICE; AND FEED-BACK MEANS EFFECTIVE TO SUM UP THE AXIAL MOVEMENT OF SAID OUTPUT MEMBER AND APPLY A SECOND FORCE TO SAID DRIVE MEANS IN OPPOSITION TO SAID FIRST FORCE TO RETURN THE DRIVE MEANS TO SAID NEUTRAL POSITION. 